The Science of Discworld Revised Edition

shelter,’ said Ponder Stibbons.
    ‘There we are, then,’ said the Senior Wrangler. ‘Personal property. Once something is yours, of course you want to improve it. The first step on the road to progress.’
    ‘I’m not sure it’s got actual legs,’ said Ponder.
    ‘The first slither, then,’ said the Senior Wrangler, as the rock slipped from the creatures tentacles. ‘We should help it,’ he added firmly. ‘After all, it wouldn’t be here if it wasn’t for us.’
    ‘Hold on, hold on,’ said the Lecturer in Recent Runes. ‘It’s only making a shelter. I mean, the Bower Bird builds intricate nests, doesn’t it? And the Clock Cuckoo even builds a clock for its mate, and no one says they’re
intelligent
as such.’
    ‘Obviously not,’ said the Dean. ‘They never get the numerals right, the clocks fall apart after a few months, and they generally lose two hours a day. That doesn’t sound like intelligence to
me
.’
    ‘What are you suggesting, Runes?’ said Ridcully.
    ‘Why don’t we send young Rincewind down again in that virtually-there suit? With a trowel, perhaps, and an illustrated manual on basic construction?’
    ‘Would they be able to see him?’
    ‘Er … gentlemen …’ said Ponder, who had been letting the eye of the omniscope drift further into the shallows.
    ‘I don’t see why not,’ said Ridcully.
    ‘Er … there’s a … there’s …’
    ‘It’s one thing to push planets around over millions of years, but at this level we couldn’t even give our builder down there a heavy pat on the back,’ said the Dean. ‘Even if we knew which part of him was his back.’
    ‘Er …
something’s paddling, sir! Something’s going for a paddle, sir!
’
    It was probably the strangest cry of warning since the famous ‘Should the reactor have gone that colour?’ The wizards clustered around the omniscope.
    Something had gone for a paddle. It had hundreds of little legs.

THIRTY
UNIVERSALS AND PAROCHIALS

    CHANCE MAY HAVE played a greater role than we imagine in ensuring our presence on the Earth. Not only aren’t we the pinnacle of evolution: it’s conceivable that we very nearly didn’t appear at all. On the other hand, if life had wandered off the particular evolutionary track that led to us, it might well have blundered into something similar instead. Intelligent crabs, for example. Or very brainy net-weaving jellyfish.
    We have no idea how many promising species got wiped out by a sudden drought, a collapse of some vital resource, a meteorite strike, or a collision with a comet. All we have is a record of those species that happen to have left fossils. When we look at the fossil record, we start to see a vague pattern, a tendency towards increasing complexity. And many of the most important evolutionary innovations seem to have been associated with major catastrophes …
    When we look at today’s organisms, some of them seem very simple while others seem more complex. A cockroach looks a lot simpler than an elephant. So we are liable to think of a cockroach as being ‘primitive’ and an elephant as ‘advanced’, or we may talk of ‘lower’ and ‘higher’ organisms. We also remember that life has evolved, and that today’s complex organisms must have had simpler ancestors, and unless we are very careful we think of today’s ‘primitive’ organisms as being typical of the ancestors of today’s complex organisms. We are told that humans evolved from something that looked more like an ape, and we conclude that chimpanzees are more primitive, in an evolutionary sense, than we are.
    When we do this, we confuse two different things. One is a kind of catalogue-by-complexity of
today’s
organisms. The other is a catalogue-by-time of today’s organisms, yesterday’s ancestors, the day before ’s ancestors-of-ancestors, and so on. Although today’s cockroach may be primitive in the sense that it is simpler than an elephant, it is
not
primitive in the sense of being an ancient ancestral organism. It can’t be: it’s
today’s
cockroach, a dynamic go-ahead cockroach that is ready to face the challenges of the new millennium.
    Although ancient fossil cockroaches have the same appearance as modern ones, they operated against a different backgrounds. What you needed to be a viable cockroach in the Cretaceous was probably rather different from what you need to be a viable cockroach today. In particular, the DNA of a Cretaceous cockroach was probably significantly